In prior art, as a method for cutting food material mass-produced and pushed out sequentially in a bar shape by requied quantity, such a method is well-known that with some square shaped cutters being located at each vertex of a regular polygon, food material is pushed into the cutting area enclosed by each cutter so as to squeeze and cut at the proper position by moving each cutter slidably and straightly at once to the central direction of the polygon. This art is the public domain by Japanese Utility Model Publication No. 63-29433 and Japanese Patent Publication No. 1-42652.
This cutting method, however, has practically various disadvantages as follows:
According to this cutting method, each cutter must be slid straightly to each different direction, which complicates movement transmission system of the machine, and every cutter, osculating each other on their planes, performs sliding movement, which results in large sliding friction and clumsy cutting movement. Additionally, chips of food are packed in the sliding planes, and it prevents cutters from moving at last.
Therefore, the present inventor has developed an apparatus for cutting a bar-shaped food material operated only by simple rotational movement instead of straight-sliding movement of each cutter, under EPC Publication No. EP 0 553 958 A1 and PCT International Application No. PCT/JP93/00644. As shown in FIG. 1 and FIG. 2, in this apparatus, several cutters of similar shape are pivotally arranged along the circumference at regular intervals so as to make a distal end (e.sub.0) of each cutter move slidably along the side fringe (e.sub.1) of its neighbouring cutter, and while keeping contact relationship among cutters, a cutting gate (g), generated by rotating each cutter at once, is opened and closed, or magnified and reduced. When the cutting gate (g) is opened, a bar-shaped food is conveyed into this cutting gate (g), referring to FIG. 1, and then by gathering each distal end (e.sub.0) of the cutters at one point to close the cutting gate (g), the bar-shaped food is constricted to be cut as shown in FIG. 2.
According to this apparatus, since sliding portion accompanied by opening and closing the cutting gate (g) is restricted to the portion of each distal end (e.sub.0) of the cutters, sliding friction becomes very small, and without adding any excessive force to each portion of cutting system, smoothly cutting movement of each cutter is enabled, and therefore, the cutting process of bar-shaped food material can be actually achieved sequentially for a long time.
However, this apparatus to which these rotational cutters are adapted has such a problem that for the kind of food material, for example, viscous rice paste or Turkish paste, a small protrusion (i) and a cone shaped protrusion (j) like threading line are formed on the cut processed surface of food (F') as shown in FIG. 4, and especially in case of supplying the food required for solid state, it causes a serious problem.
In cutting apparatus developed by prior art, at the time of rotating each cutter and gathering its distal end (e.sub.0) at one point as referred to FIG. 2, in theory, the cutting gate (g) can be completely closed so as to make a clear cutting of the bar-shaped food, but in practice, in order to work a driving system of the cutter normally, the interstice among the distal ends (e.sub.0) of all cutters cannot be tightly made as "zero", but a very small interstice must be provided among these distal ends. Accordingly, remnants of the food material are to exist in this small interstice, which results in leaving a thread shaped protrusion (i) at the center on the cutting surface without being cut completely.
So far, in order to solve this problem of thread shaped protrusion, it has been tried to chamfer the edge portion of the side fringe (e.sub.1) of the cutter, thereby to reduce the width of vertical plane of the fringe (e.sub.1) less than the thickness of the cutter. In this method, however, a thread shaped protrusion (i) can be reduced to some degree, but it cannot be prevented completely. Accordingly, as for the particular food material, for example, like sweet bean paste with very small viscosity, a cone shaped protrusion (j) is unavboidably formed on the cutting surface as shown in FIG. 4.
In this way, the above-mentioned problem cannot be solved essentially by the prior cutting ideas. Especially, in the case of cutting food material with small viscosity, this protrusion is so remarkable that after the cutting operation, another second device for reshaping should be needed, or else manual treament is furnished to reshape the cutting surface roundly.
Therefore, the present invention hat an object to provide a method for cutting a bar-shaped food and its apparatus capable of cutting completely various bar-shaped food materials extruded sequentially without leaving any protrusion on the cutting surface as required, while making its surface roundly.
Further, another object of the present invention is to provide a bar-shaped food cutting method and its apparatus capable of cutting a bar-shaped food having core including not less than two kinds of food materials extruded sequentially as the core material to be correctly wrapped by an outer covering material, without leaving any protrusion on the cutting surface while making its surface smooth.